1. Field of the Invention
The present invention generally relates to a position apparatus and a position method thereof, and more particularly, to a position apparatus capable of enhancing accuracy of positioning a touch position and a position method thereof.
2. Description of Related Art
With the rapid development of technology, most electronic devices, such as notebook computers, mobile phones, or portable multimedia players, usually have touch panels serving as input interfaces of a new generation in replacement of conventional keyboards. The touch panels are generally classified into capacitive, resistive, infrared, and ultrasonic touch panels, wherein the resistive touch panels and the capacitive touch panels are the most common products. The capacitive touch panels are operated by approaching or touching the touch panels with a finger or a conductive material to change capacitances of the touch panels. While variations in the capacitances are detected, the location approached or touched by the finger or the conductive material is determined, and an operation corresponding to the approached or touched location is performed. The capacitive touch panels have a multi-touch feature which allows a more user-friendly operation. Therefore, the capacitive touch panels are gradually favored by the market.
In U.S. Pat. No. 5,825,352, a multiple-finger contact sensing method is provided. The multiple-finger contact sensing method includes a process for determination of a touch position according to peaks and valleys in a capacitive curve. In the above-described patent, capacitances sensed by neighboring sensors are compared in sequence, and then, positions of the peaks and the valleys are found according to a rising or falling trend of the capacitive curve. When the sensors are scanned in a single axis, such as the X-axis or the Y-axis, the detected peak values and the positions of the peaks are stored. If the peak values are greater than a reference threshold, the positions of the peaks are determined to be touched. The peak values and the neighboring valley values are calculated, so that the touch position touched by the multiple fingers on the touch panel is obtained.
However, when the touch panel is untouched, the capacitances sensed by the sensors have noises caused by variations in environmental factors. In the above-described process, the touch position is determined after the peaks and the valleys are detected. Accordingly, the capacitances due to noises are possibly considered as the peaks and then stored, and whether the positions of the peaks refer to the touch position is further determined. Meanwhile, calculating the capacitances caused by the noises not only wastes the calculation resources of the system but also results in unnecessary power consumption of the system. Moreover, in the calculating method for positioning the touch position, the centroid position obtained from the capacitances sensed by the sensors is the touch position. For some sensor, the capacitances sensed by the sensors when the touch position is in the center of the sensor are different from the capacitances sensed by the sensors when the touch position is on the edges of the sensor. Accordingly, the accuracy of positioning the touch position by calculation is affected.